FRIDAY, Sept. 28 (HealthDay News) -- Eye proteins that can kill harmful bacteria may prove useful in developing new powerful and inexpensive antimicrobial drugs, according to a new study.

The finding was made by University of California, Berkeley, researchers investigating why eyes are so resistant to infection. They noticed that there is no bacteria living on the surface of the eye, unlike other surfaces of the body.

They also discovered that tissue from the eye's cornea -- the transparent part of the eye that covers the pupil and iris -- could destroy a number of types of bacteria in lab experiments.

"It is very difficult to infect the cornea of a healthy eye. We've even used tissue paper to damage the eye's surface cells and then plastered them with bacteria, and still had trouble getting bacteria to enter the cornea. So we proposed that maybe there were antimicrobial factors that are unique to the eye," study principal investigator Suzanne Fleiszig, a professor at UC Berkeley's School of Optometry who specializes in infectious diseases and microbiology, said in a university news release.

Further research revealed that small fragments of keratin protein in the eye play an important role in fighting bacteria. Fleiszig and her team then created synthetic versions of these keratin fragments and found that they destroyed bacteria that can lead to flesh-eating disease and strep throat, diarrhea, staph infections and cystic fibrosis lung infections.

The keratin fragments are relatively easy to make, which makes them good candidates for low-cost antimicrobial drugs, the researchers said.

"What's really exciting is that the keratins in our study are already in the body, so we know that they are not toxic, and that they are biocompatible," Fleiszig said. "The problem with small, naturally occurring, antimicrobial molecules identified in previous research is that they were either toxic or easily inactivated by concentrations of salt that are normally found in our bodies."

The study appears in the October issue of the Journal of Clinical Investigation.